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Abstract:

The distance measurement and photometry device includes: a case having an
opening in its front surface; a rectangular lens array which is located
on a front surface side of the case, which is made of a transparent resin
material, and in which first and second distance measurement lenses and a
photometry lens located between the distance measurement lenses are
integrally formed in line; an image sensor board which is shaped like a
thin plate, which is arranged on a back surface side of the case, and
which is located opposed to the lens array; and two-dimensional distance
measurement image sensors and photometry image sensor which are arranged
on the image sensor board.

Claims:

1. A distance measurement and photometry device comprising: a pair of
distance measurement sensors arranged at a predetermined interval; a
photometry sensor arranged between the distance measurement sensors; a
pair of distance measurement lenses to form images of a distance
measurement target on the distance measurement sensors, respectively; a
photometry lens to form an image of the distance measurement target on
the photometry sensor; a distance calculation unit to calculate a
distance to the distance measurement target on the basis of a signal
outputted from each of the distance measurement sensors; and a photometry
calculation unit to calculate brightness of the distance measurement
target on the basis of a signal outputted from the photometry sensor,
wherein the distance measurement sensors and the photometry sensor are
formed on a single sensor board and are each a two-dimensional sensor
having a plurality of light receiving elements arranged in a planar
fashion.

2. The distance measurement and photometry device according to claim 1,
wherein the distance measurement sensors and the photometry sensor have
the same size and the same number of pixels, and are integrally cut out
from a semiconductor wafer having a plurality of image sensors of a
predetermined size formed thereon through a semiconductor process.

3. The distance measurement and photometry device according to claim 1,
wherein the distance calculation unit calculates the distance to the
distance measurement target by calculating a parallax between images of
the distance measurement target formed on certain pixels of the distance
measurement sensors, respectively, on the basis of pixel output signals
outputted from the respective distance measurement sensors and
corresponding to the respective images of the distance measurement
target.

4. The distance measurement and photometry device according to claim 1,
wherein a plurality of the photometry sensors are arranged between the
distance measurement sensors, and a plurality of the photometry lenses to
form images of the distance measurement target on the respective
photometry sensors are arranged, and the photometry lenses are formed to
have different angles of view, respectively.

5. An imaging apparatus in which an object image is formed on an image
sensor through an imaging lens system and image data is generated on the
basis of a pixel output signal outputted from the image sensor and
corresponding to the object image, the imaging apparatus comprising the
distance measurement and photometry device according to claim 1 for
measuring a distance to an object and brightness of the object.

6. The imaging apparatus according to claim 5, wherein a pixel output
signal outputted from at least one of a plurality of pixel regions, into
which the entire pixel plane of each of the distance measurement sensors
is divided, is outputted to the distance calculation unit in distance
measurement.

7. The imaging apparatus according to claim 5, wherein the imaging lens
system has an optical zoom function, and when the object is imaged with
the imaging lens system zoomed in to a telephoto side, a pixel output
signal outputted from any one of a pixel region of the entire pixel plane
of each of the distance measurement sensors and a partial pixel region
which is a part of the pixel region is outputted to the distance
calculation unit in distance measurement, the pixel region corresponding
to an imaging region obtained by zooming in the imaging lens system to
the telephoto side.

8. The imaging apparatus according to claim 5, further comprising another
distance calculation unit to calculate a distance to the object on the
basis of a pixel output signal outputted corresponding to the object
image formed on the image sensor, wherein a focus operation of the
imaging lens system is performed on the basis of both or a selected one
of information on a distance to the object calculated by the other
distance calculation unit and information on a distance to the object
calculated by the distance measurement and photometry device.

Description:

[0001] CROSS-REFERENCE TO THE RELATED APPLICATION

[0002] This application is based on and claims the priority benefit of
Japanese Patent Application No. 2010-22353, filed on Feb. 3, 2010, the
contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a distance measurement and
photometry device for measuring a distance to a measurement target as
well as measuring the brightness of the measurement target, and to an
imaging apparatus, such as a digital still camera or a digital video
camera, including the distance measurement and photometry device.

[0005] 2. Description of the Related Art

[0006] Heretofore, in a digital still camera (hereinafter called a
"digital camera") and the like including external measurement type
distance measurement device and photometry device, the distance
measurement device and the photometry device are integrated into one unit
for reduction in size of a camera main body and the like (see Japanese
Patent No. 3958055, for example).

[0007] A distance measurement and photometry device shown in Japanese
Patent No. 3958055 includes multiple pairs of distance measurement line
sensors and multiple photometry sensors arranged between the multiple
pairs of distance measurement line sensors, the distance measurement line
sensors and the photometry sensors being arranged on a single chip.

[0008] However, since the distance measurement line sensors are arranged
for the entire image plane in a digital camera including the conventional
external measurement type distance measurement and photometry device, the
digital camera can perform distance measurement only on three distance
measurement regions, i.e., a central portion of the image plane and
portions to the right and left of the central portion. This poses a
problem that distance measurement cannot be performed on a main object
accurately if the main object is located near an upper left portion of
the image plane which is outside the distance measurement regions, for
example. Further, regions in which photometry is performed by the
photometry sensors are located near the three distance measurement
regions. This poses another problem that photometry cannot be performed
on a main object accurately if the main object is located near an upper
left portion of the image plane which is outside the photometry regions,
for example.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is to provide a distance
measurement and photometry device and an imaging apparatus using the
distance measurement and photometry device which allow performing
accurate distance measurement and photometry wherever a measurement
target is.

[0010] To achieve the above object, a distance measurement and photometry
device according to an embodiment of the present invention includes: a
pair of distance measurement sensors arranged at a predetermined
interval; a photometry sensor arranged between the distance measurement
sensors; a pair of distance measurement lenses configured to form images
of a distance measurement target on the distance measurement sensors,
respectively; a photometry lens configured to form an image of the
distance measurement target on the photometry sensor; a distance
calculation unit configured to calculate a distance to the distance
measurement target on the basis of a signal outputted from each of the
distance measurement sensors; and a photometry calculation unit
configured to calculate brightness of the distance measurement target on
the basis of a signal outputted from the photometry sensor. The distance
measurement sensors and the photometry sensor are formed on a single
sensor board and are each a two-dimensional sensor having a plurality of
light receiving elements arranged in a planar fashion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a front view showing a digital camera which is an example
of an imaging apparatus including a distance measurement and photometry
device according to a first embodiment of the present invention.

[0012]FIG. 2 is a block diagram showing a brief system configuration of
the digital camera according to the first embodiment.

[0013]FIG. 3 is a schematic cross-sectional side view showing the
distance measurement and photometry device according to the first
embodiment.

[0014]FIG. 4 is a plan view showing paired distance measurement image
sensors and a photometry image sensor of the distance measurement and
photometry device according to the first embodiment.

[0015]FIG. 5 is a schematic view illustrating the principle of distance
measurement by the distance measurement and photometry device.

[0016]FIG. 6 is a plan view showing multiple image sensors formed on a
semiconductor wafer.

[0017]FIG. 7 is a block diagram showing a brief system configuration of
the digital camera according to a second embodiment.

[0018]FIG. 8A is a view showing an example of an image taken with lenses
zoomed out to a wide-angle side, and FIG. 8B is a view showing an example
of an image taken with the lens system zoomed in to a telephoto side.

[0019]FIG. 9A is a side view showing paired distance measurement lenses
and three photometry lenses, which are different in angle of view, of a
distance measurement and photometry device according to the second
embodiment of the present invention, and FIG. 9B is a side view showing
paired distance measurement image sensors and three photometry image
sensors, which are arranged between the sensors, of the distance
measurement and photometry device according to the second embodiment.

[0020]FIG. 10A is a view showing five distance measurement frame regions
set in the pixel plane of each distance measurement image sensor of the
distance measurement and photometry device according to the second
embodiment, and FIG. 10B is a view showing a distance measurement target
region set near the center of the entire pixel plane of each distance
measurement image sensor when the imaging angle of view of the imaging
lens system 2 is shifted to the telephoto side.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Preferred embodiments of the present invention will be explained in
detail hereinafter with reference to the accompanying drawings.

First Embodiment

[0022]FIG. 1 shows a digital camera which is an example of an imaging
apparatus including a distance measurement and photometry device
according to a first embodiment of the present invention.

[0023] (Exterior Configuration of Digital Camera)

[0024] As shown in FIG. 1, on a front surface (anterior surface) side of a
digital camera 1 according to this embodiment, an imaging lens system 2,
a lens array 4, and the like are arranged. The lens array 4 is located on
a front surface side of a distance measurement and photometry device 3.
On a surface of the lens array 4, first and second distance measurement
lenses 5a and 5b and a photometry lens 6 are formed integrally (the
distance measurement and photometry device 3 will be described in detail
later). The first and second distance measurement lenses 5a and 5b are
arranged in a horizontal direction at a predetermined interval. The
photometry lens 6 is arranged between the first and second distance
measurement lenses 5a and 5b. The imaging lens system 2, the first and
second distance measurement lenses 5a and 5b, and the photometry lens 6
have optical axes parallel to one another.

[0025] (System Configuration of Digital Camera 1)

[0026] As shown in FIG. 2, the digital camera 1 includes: the imaging lens
system 2 having multiple lens groups; an aperture unit 10 having a
shutter function; a CCD image sensor 11 being a solid-state image sensor
configured to form an image of an object image coming through the imaging
lens system 2, on a light-receiving surface; a signal processor 12
configured to capture an imaging signal (electric signal) outputted from
each pixel of the CCD image sensor 11 and to convert the captured signal
into image data which can be displayed and recorded; a manipulation part
13 including a release button 7, an imaging mode switching button 8, and
the like (see FIG. 1); a controller 14 configured to perform control on
the entire system of the digital camera 1 based on a control program
stored in a ROM (not shown) in response to manipulation input information
from the manipulation part 13; a liquid crystal monitor (LCD) 15
configured to display the image data generated by the signal processor
12; a focusing lens driving part 16 configured to drive a focusing lens
group of the imaging lens system 2; an aperture unit driving part 17
configured to drive the aperture unit 10; the external measurement type
distance measurement and photometry device 3 configured to measure a
distance to an object and to measure the brightness of the object; and
the like. The image data generated by the signal processor 12 is stored
in a memory card 18 which is detachable from the digital camera 1.

[0028] As shown in FIGS. 3 and 4, the distance measurement and photometry
device 3 includes: a case 20 having an opening in its front surface
(upper side in FIG. 3); the rectangular lens array 4 which is located on
a front surface side of the case 20, which is made of a transparent resin
material, and in which the first and second distance measurement lenses
5a and 5b and the photometry lens 6 are integrally formed in line (in a
horizontal direction of the digital camera 1); an image sensor board 21
which is shaped like a thin plate, which is arranged on a back surface
side (lower side in FIG. 3) of the case 20, and which is located opposed
to the lens array 4; distance measurement image sensors 22a and 22b being
planar (two-dimensional) distance measurement sensors arranged on the
image sensor board 21; a photometry image sensor 23 being a planar
(two-dimensional) photometry sensor arranged on the image sensor board
21; and a circuit board 24 arranged on the back surface of the image
sensor board 21.

[0029] The paired planar distance measurement image sensors 22a and 22b
are arranged opposed to the first and second distance measurement lenses
5a and 5b. Meanwhile, the planar photometry image sensor 23 located
between the distance measurement image sensors 22a and 22b is arranged
opposed to the photometry lens 6.

[0030] The planar light-receiving surfaces of the respective distance
measurement image sensors 22a and 22b and photometry image sensor 23 have
the same size and the same number of pixels. Moreover, a predetermined
gap is provided between the photometry image sensor 23 and each of the
distance measurement image sensors 22a and 22b.

[0031] The distance measurement image sensors 22a and 22b and the
photometry image sensor 23 on the image sensor board 21 are image
sensors, such as CCDs or CMOSs, integrally formed on a semiconductor
wafer with a known semiconductor process, and each having multiple light
receiving elements (pixels) arranged in a lattice (the distance
measurement image sensors 22a and 22b and the photometry image sensor 23
will be described in detail later).

[0032] The optical axes of the respective first and second distance
measurement lenses 5a and 5b and photometry lens 6 are parallel to one
another. The diagonal centers of the light receiving surfaces of the
distance measurement image sensors 22a and 22b and photometry image
sensor 23 are positioned to substantially match the optical axes of the
lenses (the first and second distance measurement lenses 5a and 5b and
the photometry lens 6), respectively.

[0033] The first and second distance measurement lenses 5a and 5b have
such focal distances that light beams from the object that have entered
the first and second distance measurement lenses 5a and 5b may form
images on surfaces of the distance measurement image sensors 22a and 22b,
respectively. The photometry lens 6 has such a focal distance that a
light beam from the object that has entered the photometry lens 6 may
form an image on a surface of the photometry image sensor 23.

[0034] Further, it is designed such that the angles of view of the first
and second distance measurement lenses 5a and 5b and photometry lens 6
may be each substantially equal to the angle of view of the imaging lens
system 2. This allows the distance measurement and photometry device 3 to
perform distance measurement and photometry on the entire image plane
that covers the entire light receiving surface (imaging region) of the
CCD image sensor 11.

[0035] The circuit board 24 is provided with a distance measurement
calculation part 25, a photometry calculation part 26, and the like. The
distance measurement calculation part 25 is configured to capture pixel
output signals outputted from the pixels of the distance measurement
image sensors 22a and 22b and to calculate a distance to the object by
calculating the displacement (parallax) between the object images
respectively formed on the distance measurement image sensors 22a and
22b. The photometry calculation part 26 is configured to capture pixel
output signals outputted from the pixels of the photometry image sensor
23 and to calculate the brightness of the object.

[0036] The distance information thus calculated by the distance
measurement calculation part 25 and the brightness information thus
calculated by the photometry calculation part 26 are outputted to the
controller 14. The controller 14 includes a distance calculation unit
configured to calculate a distance to a distance measurement target on
the basis of the signals outputted from the distance measurement sensors,
and a photometry calculation unit configured to calculate the brightness
of the distance measurement target on the basis of the signals outputted
from the photometry sensor. The controller 14 outputs a drive control
signal to the focusing lens driving part 16 on the basis of the inputted
distance information so that the camera may be focused on the object, and
outputs a drive control signal to the aperture unit driving part 17 on
the basis of the inputted brightness information so that the object may
be correctly exposed.

[0037] Now, description will be given of the principle of distance
measurement performed by the distance measurement and photometry device
3.

[0038] As shown in FIG. 5, an image of a certain point on an object A is
formed on the surface of the distance measurement image sensor 22a as an
object image a1 and an image of the certain point is formed on the
surface of the distance measurement image sensor 22b as an object image
a2 with the object images a1 and a2 displaced from each other by a
parallax Δ. The images are then received by the multiple light
receiving elements (pixels) and converted into electric signals. Note
that, in FIG. 5, the photometry lens 6 arranged between the first and
second distance measurement lenses 5a and 5b and the photometry image
sensor 23 arranged between the distance measurement image sensors 22a and
22b are omitted.

[0039] The following formula (1) is satisfied when Δ indicates the
parallax, D indicates a distance between the optical axes of the first
and second distance measurement lenses 5a and 5b (base-line length), L
indicates a distance between the object A and each of the first and
second distance measurement lenses 5a and 5b, f indicates a focal
distance of each of the first and second distance measurement lenses 5a
and 5b, and when L>>f.

L=Df/Δ formula (1)

[0040] Since D and f are known, the distance L between the object A and
each of the first and second distance measurement lenses 5a and 5b can be
calculated by causing the distance measurement calculation part 25 to
calculate the parallax Δ with a well-known calculation method from
the pixel output signals respectively outputted from the pixels (light
receiving elements) of the distance measurement image sensors 22a and
22b.

[0041] Note that, if the distance (base-line length) D between the optical
axes of the first and second distance measurement lenses 5a and 5b is too
small, the parallax Δ is too small to calculate the distance L to
the object A accurately.

[0043] Next, description will be given of a distance measurement and
photometry operation performed by the distance measurement and photometry
device 3 when an object is imaged with the digital camera 1.

[0044] When a photographer half-presses the release button 7 while the
power switch is ON, the controller 14 outputs a distance measurement and
photometry start instruction signal to the distance measurement and
photometry device 3. Light beams from the object that have entered the
first and second distance measurement lenses 5a and 5b form images on the
surfaces of the distance measurement image sensors 22a and 22b,
respectively, and a light beam that has entered the photometry lens 6
forms an image on the surface of the photometry image sensor 23. As
described above, the distance measurement calculation part 25 captures
the pixel output signals outputted from all the pixels of the distance
measurement image sensors 22a and 22b and calculates a distance to the
object by calculating the displacement (parallax) between the object
images respectively formed on the distance measurement image sensors 22a
and 22b. In this event, the photometry calculation part 26 captures the
pixel output signals outputted from the pixels of the photometry image
sensor 23 and calculates the brightness of the object on the basis of the
magnitude of the pixel outputs. The information on the distance to the
object and the information on the brightness of the object thus
calculated are outputted to the controller 14.

[0045] The controller 14 performs control to drive the focusing lens
driving part 16 on the basis of the inputted distance information.
Thereby, the focusing lens driving part 16 moves the focusing lens group
of the imaging lens system 2 to a focused position so that an object
image may be formed on the light receiving surface of the CCD image
sensor 11.

[0046] The controller 14 also performs control to drive the aperture unit
driving part 17 on the basis of the inputted brightness information.
Thereby, the aperture unit driving part 17 sets an opened state of the
aperture unit 10 (aperture value), the number of actuations of the
electronic shutter of the CCD image sensor 11, and the like so that the
object may be correctly exposed.

[0047] When the release button 7 is fully pressed, the object is imaged
under a focused state and with appropriate exposure conditions (the
number of actuations of the electronic shutter of the CCD image sensor
11, the aperture value of the aperture unit 10, and the like). Then, the
signal processor 12 captures imaging signals outputted from the pixels of
the CCD image sensor 11 and converts the captured signals into image data
which can be displayed and recorded. The image data generated by the
signal processor 12 is displayed on the liquid crystal monitor (LCD) 15
as an image, or recorded in the memory card 18.

[0048] As described above, according to the digital camera 1 including the
distance measurement and photometry device 3 of this embodiment, the
distance measurement and photometry device 3 is capable of performing
accurate distance measurement and photometry on a wide range over the
entire image plane on the basis of the pixel output signals outputted
from the entire pixel plane of each of the planar distance measurement
image sensors 22a and 22b and photometry image sensor 23. This allows the
digital camera 1 to accurately measure the distance to the object and the
brightness of the object wherever the object is in the image plane,
thereby achieving a high-quality image.

[0049] Next, the distance measurement image sensors 22a and 22b and the
photometry image sensor 23 of the distance measurement and photometry
device 3 will be described in detail.

[0050] The paired distance measurement image sensors 22a and 22b and the
photometry image sensor 23 on the image sensor board 21 are integrally
formed on a semiconductor wafer with a known semiconductor process, and
pixels are patterned on each sensor with a mask. In the patterning, a
mask having such a pattern that the pixel matrices of the distance
measurement image sensors 22a and 22b and the photometry image sensor 23
are parallel to one another is used. Moreover, since a surface of the
semiconductor wafer is planar, the normals to the respective distance
measurement image sensors 22a and 22b and photometry image sensor 23 are
necessarily parallel to one another. Thereby, the distance measurement
image sensors 22a and 22b are arranged without any angular displacement
of their light receiving surfaces, thus allowing accurate distance
measurement.

[0051] Further, the distance measurement image sensors 22a and 22b and the
photometry image sensor 23 of the distance measurement and photometry
device 3 which are used in this embodiment are significantly smaller in
size than the image sensor of the CCD image sensor 11 used in the digital
camera 1 for the imaging of the object. Thus, for example, image sensors
of camera modules generally implemented in mobile phones and the like can
be used as the distance measurement image sensors 22a and 22b and the
photometry image sensor 23 of the distance measurement and photometry
device 3.

[0052] Such image sensors for camera modules of mobile phones are
mass-produced and thus advantageous in terms of cost. Image sensors of
VGA (640×480 pixels) size are especially low in cost. Such image
sensors of VGA size are as large as approximately 1/10 inches.

[0053] As shown in FIG. 6, three adjacent image sensors arranged in line
(for example, three image sensors shown in diagonal lines) are cut out
from a semiconductor wafer 30 having multiple image sensors 31 of VGA
size formed thereon through a known semiconductor process. Thereby, the
image sensor board 21 as shown in FIG. 4 in which the paired distance
measurement image sensors 22a and 22b and the photometry image sensor 23
located between the sensors 22a and 22b are integrally formed on its
surface can be achieved easily and at low cost. Thus, the distance
measurement and photometry device 3 can be reduced in cost.

[0054] Further, it is not necessary to add a process such as implementing
the distance measurement image sensors 22a and 22b and the photometry
image sensor 23 located between the sensors 22a and 22b, which are used
in the distance measurement and photometry device 3, on the image sensor
board 21 with these sensors individually positioned on the board 21. This
allows keeping a state where the distance measurement image sensors 22a
and 22b and the photometry image sensor 23 located between the sensors
22a and 22b are accurately positioned on the image sensor board 21 for a
long period, and thereby allows performing accurate distance measurement
for a long period.

Second Embodiment

[0055]FIG. 7 is a block diagram showing a digital camera which is an
example of an imaging apparatus including a distance measurement and
photometry device according to a second embodiment of the present
invention.

[0056] As shown in FIG. 7, a digital camera 1a of this embodiment includes
a zoom lens group in the imaging lens system 2, and thus includes a zoom
lens driving part 19. Further, the controller 14 includes an auto-focus
controller (hereinafter called "AF controller") 14a configured to perform
auto-focus control based on imaging signals captured from the CCD image
sensor 11. The configuration of the digital camera 1a excluding a
distance measurement and photometry device 3a is the same as that of the
first embodiment shown in FIG. 2, and thus overlapping description will
be omitted (the distance measurement and photometry device 3a of this
embodiment will be described in detail later).

[0057] In this embodiment, the zoom lens group is included in the imaging
lens system 2. Hence, in a case where the digital camera 1a has a 28 mm
to 300 mm (35 mm equivalent) high-powered optical zoom function, for
example, as shown in FIGS. 8A and 8B, an extreme wide-angle (FIG. 8A) and
an extreme telephoto (FIG. 8B) are greatly different in imaging angle of
view (imaging range). Note that, in FIGS. 8A and 8B, two persons at the
center are an object.

[0058] In this manner, in the digital camera 1a including the high-powered
optical zoom function, the extreme wide-angle and the extreme telephoto
are greatly different in imaging angle of view. The imaging angle of view
at the time of imaging with the lens system zoomed in to the extreme
telephoto is far smaller than the imaging angle of view of the extreme
wide-angle. Now assume a case where only a set of the photometry lens and
the photometry image sensor is provided in the distance measurement and
photometry device 3 as in the first embodiment and where the angle of
view of the photometry lens is set to the imaging angle of view of the
extreme wide-angle, for example. In this case, when the object is imaged
with the lens system zoomed in to the extreme telephoto and if a bright
light source and the like is provided outside the imaging angle of view
at the time of imaging, photometry has to be performed with the
brightness of the light source taken into account since the angle of view
of the photometry lens is set to the imaging angle of view of the extreme
wide-angle. For this reason, photometry sometimes cannot be performed
appropriately for the object within the imaging angle of view at the time
of imaging.

[0059] To address this problem, in the distance measurement and photometry
device 3a of this embodiment, three photometry lenses 6a, 6b, and 6c
different in angle of view are formed in line between the paired first
and second distance measurement lenses 5a and 5b formed on both sides of
the lens array 4, and the paired distance measurement image sensors 22a
and 22b and three photometry image sensors 23a, 23b, and 23c are formed
on the image sensor board 21 to be opposed to the first and second
distance measurement lenses 5a and 5b and the photometry lenses 6a, 6b,
and 6c, respectively, as shown in FIGS. 9a and 9b. Note that, the
distance measurement image sensors 22a and 22b and the three photometry
image sensors 23a, 23b, and 23c have the same size and the same number of
pixels. The configuration of the distance measurement and photometry
device 3a other than above is the same as that of the distance
measurement and photometry device 3 of the first embodiment.

[0060] In this embodiment also, as shown in FIG. 6, five adjacent image
sensors arranged in line are cut out from the semiconductor wafer 30
having the multiple image sensors 31 of VGA size formed thereon through
the known semiconductor process. Thereby, the image sensor board 21 as
shown in FIG. 9B in which the paired distance measurement image sensors
22a and 22b and the three photometry image sensors 23a, 23b, and 23c
located between the sensors 22a and 22b are integrally formed on its
surface can be achieved easily and at low cost.

[0061] In this embodiment, in a case where the imaging lens system 2 has a
28 mm to 300 mm (35 mm equivalent) high-powered optical zoom function, an
angle of view θ1 of the photometry lens 6a is set to an angle
equivalent to a focal length of approximately 150 mm (35 mm equivalent),
an angle of view θ2 of the photometry lens 6b is set to an angle
equivalent to a focal length of approximately 28 mm (35 mm equivalent),
and an angle of view θ3 of the photometry lens 6c is set to an
angle equivalent to a focal length of approximately 300 mm (35 mm
equivalent), for example. Note that, in this embodiment, the angle of
view of the paired first and second distance measurement lenses 5a and 5b
is set to an angle equivalent to a focal length of approximately 28 mm
(35 mm equivalent).

[0063] Next, description will be given of a photometry operation performed
by the distance measurement and photometry device 3a when an object is
imaged with the digital camera 1a.

[0064] The distance measurement and photometry device 3a according to this
embodiment includes the three sets of the photometry lenses 6a, 6b, and
6c different in photometry angle of view and the photometry image sensors
23a, 23b, and 23c. Thus, when the imaging angle of view of the imaging
lens system 2 of the digital camera 1a is changed through a zoom
manipulation by the photographer, the photometry calculation part (not
shown) selects one of the three sets of the photometry lenses 6a, 6b, and
6c and the photometry image sensors 23a, 23b, and 23c which is
appropriate in terms of photometry angle of view in response to the
information on imaging angle of view inputted from the controller 14, and
captures pixel output signals outputted from the photometry image sensor
of the selected set.

[0065] For example, when the imaging angle of view of the imaging lens
system 2 is shifted to the wide-angle side (near 28 mm (35 mm
equivalent), for example), the photometry calculation part (not shown)
captures pixel output signals outputted from the photometry image sensor
23b combined with the photometry lens 6b whose angle of view is an angle
equivalent to a focal length of approximately 28 mm (35 mm equivalent) in
response to the information on imaging angle of view inputted from the
controller 14, and calculates the brightness of the object on the basis
of the magnitude of the pixel outputs.

[0066] Moreover, when the imaging angle of view of the imaging lens system
2 is shifted to the telephoto side (near 300 mm (35 mm equivalent), for
example), the photometry calculation part (not shown) captures pixel
output signals outputted from the photometry image sensor 23c combined
with the photometry lens 6c whose angle of view is an angle equivalent to
a focal length of approximately 300 mm (35 mm equivalent) in response to
the information on imaging angle of view inputted from the controller 14,
and calculates the brightness of the object on the basis of the magnitude
of the pixel outputs.

[0067] In the same way, when the imaging angle of view of the imaging lens
system 2 is shifted to approximately the middle between the extreme
wide-angle and the extreme telephoto (near 150 mm (35 mm equivalent), for
example), the photometry calculation part (not shown) captures pixel
output signals outputted from the photometry image sensor 23a combined
with the photometry lens 6a whose angle of view is an angle equivalent to
a focal length of approximately 150 mm (35 mm equivalent) in response to
the information on imaging angle of view inputted from the controller 14,
and calculates the brightness of the object on the basis of the magnitude
of the pixel outputs.

[0068] The brightness information which is appropriate for the object and
calculated on the basis of the imaging angle of view of the imaging lens
system 2 is outputted to the controller 14. Then, the controller 14
performs control to drive the aperture unit driving part 17 on the basis
of the inputted brightness information. Thereby, the aperture unit
driving part 17 sets an opened state of the aperture unit 10 (aperture
value), the number of actuations of the electronic shutter of the CCD
image sensor 11, and the like so that the object may be correctly
exposed.

[0069] As described above, according to this embodiment, when the imaging
angle of view of the imaging lens system 2 is changed through a zoom
manipulation, one of the three sets of the photometry lenses 6a, 6b, and
6c different in photometry angle of view and the photometry image sensors
23a, 23b, and 23c which has an optimum angle of view can be selected for
photometry. Accordingly, photometry can be performed accurately
irrespective of the imaging angle of view of the imaging lens system 2
selected at the time of imaging.

[0071] Next, description will be given of a distance measurement performed
by the distance measurement and photometry device 3a when an object is
imaged with the digital camera 1a.

[0072] The first embodiment has such a configuration that distance
measurement is performed on the basis of the pixel output signals
outputted from all the pixels of the paired planar distance measurement
image sensors. On the other hand, this embodiment has such a
configuration that distance measurement is performed on the basis of
pixel output signals outputted from only a previously-set pixel region of
all the pixels of the paired planar distance measurement image sensors.

[0073] Specifically, as shown in FIG. 10A, five distance measurement frame
regions 32a, 32b, 32c, 32d, and 32e (range shown in diagonal lines) each
having a predetermined width in a horizontal direction are set in a
vertical direction at predetermined intervals in the entire pixel plane
of each of the paired distance measurement image sensors 22a and 22b, and
distance measurement is performed on the basis of pixel output signals
outputted from the distance measurement frame regions 32a, 32b, 32c, 32d,
and 32e.

[0074] Further, according to this embodiment, a distance measurement
region of a predetermined range can be set out of the entire pixel plane
of each of the distance measurement image sensors 22a and 22b in response
to a change in imaging angle of view through a zoom manipulation of the
imaging lens system 2.

[0075] Specifically, for example, when the imaging angle of view of the
imaging lens system 2 is shifted to the wide-angle side (approximately 28
mm (35 mm equivalent), for example), the distance measurement target
region is the entire pixel plane shown in FIG. 10A of each of the
distance measurement image sensors 22a and 22b. In this case, distance
measurement is performed on the basis of pixel output signals outputted
from each of the five distance measurement frame regions 32a, 32b, 32c,
32d, and 32e.

[0076] Meanwhile, when the imaging angle of view of the imaging lens
system 2 is shifted to the telephoto side (approximately 300 mm (35 mm
equivalent), for example), the distance measurement target region is a
narrow range C shown in FIG. 10B (within a frame shown in a dotted line)
located near the center of the entire pixel plane of each of the distance
measurement image sensors 22a and 22b. In this case, distance measurement
is performed on the basis of pixel output signals outputted from one
distance measurement frame region 32c located in the narrow range C
(within the frame shown in the dotted line) near the center.

[0077] In addition, when the imaging angle of view of the imaging lens
system 2 is shifted to approximately the middle between the extreme
wide-angle and the extreme telephoto, the distance measurement target
region is an intermediate region between the entire pixel plane shown in
FIG. 10A of each of the distance measurement image sensors 22a and 22b
and the narrow range C shown in FIG. 10B located near the center. In this
case, distance measurement is performed on the basis of pixel output
signals outputted from each of multiple distance measurement regions
suited to the imaging angle of view, which are selected from the five
distance measurement frame regions 32a, 32b, 32c, 32d, and 32e.

[0078] Accordingly, in this embodiment, as shown in FIG. 10A, when the
imaging angle of view of the imaging lens system 2 is shifted to the
wide-angle side (near 28 mm (35 mm equivalent), for example), the
distance measurement calculation part 25 captures pixel output signals
outputted from the five distance measurement frame regions 32a, 32b, 32c,
32d, and 32e suited to the imaging angle of view at this time and
calculates a distance to the object by calculating the displacement
(parallax) between object images.

[0079] Moreover, as shown in FIG. 10B, when the imaging angle of view of
the imaging lens system 2 is shifted to the telephoto side (near 300 mm
(35 mm equivalent), for example), the distance measurement calculation
part 25 captures pixel output signals outputted from a distance
measurement range of the central distance measurement frame region 32c
(range shown in diagonal lines) suited to the imaging angle of view at
this time and calculates a distance to the object by calculating the
displacement (parallax) between object images.

[0080] The controller 14 performs control to drive the focusing lens
driving part 16 on the basis of the distance information inputted by the
distance measurement calculation part 25. Thereby, the focusing lens
driving part 16 moves the focusing lens group of the imaging lens system
2 to a focused position so that an object image may be formed on the
light receiving surface of the CCD image sensor 11.

[0081] As described above, according to this embodiment, when the imaging
angle of view of the imaging lens system 2 is changed through a zoom
manipulation, one or more of the previously-set five distance measurement
frame regions 32a, 32b, 32c, 32d, and 32e is selected according to the
imaging angle of view of the imaging lens system 2, and distance
measurement is performed on the basis of pixel output signals outputted
from the selected distance measurement frame regions. Such a
configuration allows greatly reducing the amount of calculation as
compared to the case where distance measurement is performed on the basis
of the pixel output signals outputted from the entire pixel plane of each
of the distance measurement image sensors 22a and 22b, and thereby allows
performing distance measurement calculation processing at high speed.

[0082] When the imaging lens system 2 is zoomed in so that its imaging
angle of view may be shifted to the extreme telephoto, in particular,
distance measurement is performed only on the distance measurement range
of the central distance measurement frame region 32c (range shown in
diagonal lines) as shown in FIG. 10B. This allows further reducing the
amount of calculation and thereby allows performing distance measurement
calculation processing at higher speed. As a result, the amount of
calculation required when the object is imaged with the imaging lens
system 2 zoomed in to the telephoto side is smaller than the amount of
calculation required when the object is imaged with the imaging lens
system 2 zoomed out to the wide-angle side. Accordingly, high-speed focus
control is possible even at the time of imaging on the telephoto side in
which the amount of feed of the lens group is large (zoom magnification
is high).

[0083] (Focus Operation (Auto-focus Operation) by AF Controller 14a)

[0084] In addition to the external measurement type distance measurement
and photometry device 3, the digital camera 1a of this embodiment
includes the AF controller 14a configured to perform auto-focus control
based on imaging signals captured in the controller 14 from the CCD image
sensor 11.

[0085] The AF controller 14a captures imaging signals, which are outputted
from the CCD image sensor 11, through the signal processor 12, and
calculates an AF (auto-focus) evaluation value from the imaging signals
thus captured.

[0086] The AF evaluation value is calculated from an integrated value of
outputs from a high frequency component extraction filter, or from an
integrated value of differences in brightness between adjacent pixels,
for example. In a focused state, an edge portion of the object is clear
and thus the highest high frequency component is achieved. By using the
above characteristics, at the time of the AF operation (auto-focus
detection operation), the AF operation is executed in such a manner that
an AF evaluation value is acquired at each focus position of the imaging
lens system 2 and the position at which the largest AF evaluation value
is achieved is set as an auto-focus detection position.

[0087] Specifically, when the release button 7 (see FIG. 1) is pressed
(half-pressed), the AF controller 14a instructs the focusing lens driving
part 16 so that the focusing lens driving part 16 may be driven to move
the focusing lens group of the imaging lens system 2 in its optical axis
direction, and an AF operation of a contrast evaluation system, which is
a so-called "hill-climbing AF," is executed, for example. If an AF
(auto-focus) target range extends across the entire region from infinite
to close, the focusing lens group of the imaging lens system 2 is moved
to each focus position while being moved from close to infinite or from
infinite to close, and the AF evaluation value at the focus position is
acquired. Then, the position at which the largest AF evaluation value is
achieved is set as an auto-focus position, and the focusing lens group is
moved to the auto-focus position for focusing.

[0088] As described above, the digital camera 1a of this embodiment
includes the AF controller 14a configured to perform auto-focus control
based on imaging signals captured from the CCD image sensor 11, in
addition to the external measurement type distance measurement and
photometry device 3. The digital camera 1a thereby executes, at the same
time, the focus operation based on the distance information obtained by
the distance measurement and photometry device 3a and the focus operation
performed by the AF controller 14a. This allows focusing the camera on
the object quickly and accurately.

[0089] To be more specific, in the focus operation by the AF controller
14a, at the time of imaging on the telephoto side in which the amount of
feed of the lens group is large (zoom magnification is high), for
example, the amount of movement of the focusing lens group of the imaging
lens system 2 is increased and thus it may take time for the camera to be
focused in some cases.

[0090] To address this problem, according to this embodiment, the focusing
lens group of the imaging lens system 2 is first moved to a position near
a focus position quickly on the basis of the distance information
obtained by the distance measurement and photometry device 3a, and is
then moved to the focus position through the focus operation by the AF
controller 14a. Thereby, the range in which the focusing lens group is
moved at the time of the focus operation by the AF controller 14a can be
reduced. This allows focusing the camera on the object quickly and
accurately, and thus allows the photographer to take images without
missing the right moment to release the shutter.

[0091] Note that, it is also possible to select, through a switching
manipulation by the manipulation part 13, any one of the focus operation
based on the distance information obtained by the distance measurement
and photometry device 3a and the focus operation performed by the AF
controller 14a, and to perform the focus operation of the selected type
(on the distance measurement and photometry device 3a side, for example).

[0092] As has been described thus far, the distance measurement and
photometry device and the imaging apparatus according to the present
invention allow performing distance measurement and photometry on a
distance measurement target (object) accurately wherever the distance
measurement target (object) is, on the basis of pixel output signals
outputted from the entire pixel plane of each of the paired distance
measurement sensors and the photometry sensor located between the
distance measurement sensors, the distance measurement sensors and the
photometry sensor being two-dimensional sensors.

[0093] In the above embodiments, description has been given of the case
where the distance measurement and photometry device according to the
present invention is applied to digital cameras. Alternatively, the
distance measurement and photometry device according to the present
invention can also be implemented in digital video cameras, in-vehicle
cameras, mobile cameras, monitoring cameras, and the like as a distance
measurement and photometry device performing distance measurement and
photometry.

Patent applications by Shigeru Oouchida, Tokyo JP

Patent applications in class Optical detail with photoelement system

Patent applications in all subclasses Optical detail with photoelement system